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In a groundbreaking study published in Cell Reports, Finnish researchers have uncovered a vital role played by immune cells in the pituitary gland, opening the door to potential future treatments for endocrine disorders, including infertility.
The pituitary gland, a small pea-sized organ located at the base of the brain, is crucial for regulating essential functions in the body. It produces hormones that control growth, reproduction, blood pressure, stress responses, and water/salt balance. Without the hormones secreted by this gland, life as we know it would not be possible.
For decades, it was believed that the pituitary gland merely responds to signals from other parts of the body to adjust hormone secretion. However, new findings reveal that pituitary macrophages—immune cells residing in the gland—have a direct impact on hormone regulation.
Heli Jokela, an InFLAMES Flagship Researcher from the Turku Bioscience Center and the University of Turku, explains, “Until now, it has been thought that the pituitary gland receives messages from the rest of the body and increases or decreases hormone secretion accordingly. In fact, macrophages have a local effect on the hormone-producing cells in the pituitary.”
The research team found that the removal of macrophages led to a decrease in hormone secretion, emphasizing their critical role in the gland’s functioning. Unlike most macrophages, which originate from bone marrow during an immune response to infection, pituitary macrophages are unique in that they stem from the fetal period and regenerate themselves throughout life.
Doctoral Researcher Henna Lehtonen elaborates on this discovery: “A particularly novel finding in our study is that all pituitary macrophages originate from the fetal period, rather than from monocytes derived from the bone marrow. They also regenerate themselves to maintain their numbers.”
This revelation challenges previous assumptions about the source of immune cells in the pituitary gland, suggesting that these resident macrophages may offer new therapeutic avenues for regulating hormone secretion.
Pia Rantakari, leader of the research group, envisions that manipulating these macrophages could eventually help treat conditions caused by hormonal imbalances, such as polycystic ovary syndrome (PCOS), a leading cause of infertility. “By regulating the macrophages, it could be possible to either increase or reduce hormone secretion depending on the condition,” Rantakari notes.
However, she cautions that the therapeutic application of macrophages in treating endocrine disorders is still in its early stages and requires significant further research before it can become a feasible treatment.
This exciting discovery not only enhances our understanding of pituitary gland physiology but also provides new insights into the role of immune cells in maintaining endocrine health.
Disclaimer: The findings in this article are based on the study titled “Early precursor-derived pituitary gland tissue-resident macrophages play a pivotal role in modulating hormonal balance,” by Henna Lehtonen et al., published in Cell Reports (2025). While the research holds promise, further studies are needed to confirm the potential for macrophages as a therapeutic tool in endocrine disorders.
